Physical and Chemical Properties of Water
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Physical and Chemical Properties of Water

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Questions and Answers

What is the main component of pure water?

  • Oxygen and nitrogen
  • Hydrogen and carbon
  • Oxygen and hydrogen (correct)
  • Nitrogen and carbon

    • At what temperature does water transition from liquid to solid?

  • 50°F
  • 100°C
  • 32°F
  • 0°C (correct)

    • What defines freshwater in terms of salt content?

  • More than 2% salt
  • Between 1% and 2% salt
  • Less than 3% salt
  • Less than 1% salt (correct)

    • Which of the following is a characteristic of saltwater?

    <p>Composed of at least 3% salt</p> Signup and view all the answers

    What is a common physical state of water at temperatures above 100°C?

    <p>Gas</p> Signup and view all the answers

    Which organisms are typically found in saltwater environments?

    <p>Sharks and tuna</p> Signup and view all the answers

    What is one of the critical roles of water in chemical reactions?

    <p>It acts as a catalyst</p> Signup and view all the answers

    How does saltwater density compare to that of freshwater?

    <p>Saltwater has higher density than freshwater</p> Signup and view all the answers

    What is the primary reason distilled water becomes corrosive over time in cooling systems?

    <p>It absorbs carbon dioxide from the air.</p> Signup and view all the answers

    Which type of water is NOT recommended for use in cooling systems due to high levels of contamination and corrosiveness?

    <p>Rainwater</p> Signup and view all the answers

    What is one of the severe risks associated with using sea water in engine cooling systems?

    <p>Severe corrosion and deposits formation</p> Signup and view all the answers

    Which of the following forms of corrosion is NOT typically associated with cooling water systems?

    <p>Oxidation corrosion</p> Signup and view all the answers

    What role do corrosion inhibitors play in cooling water?

    <p>They reduce the corrosive effects of distilled water.</p> Signup and view all the answers

    How does scale affect cooling water systems?

    <p>It leads to insulation and interferes with heat transfer.</p> Signup and view all the answers

    What is a key characteristic of pitting corrosion?

    <p>It creates small, localized holes that can lead to failure.</p> Signup and view all the answers

    Why is untreated tap water specifically discouraged in cooling systems?

    <p>It can lead to chalk deposit formation.</p> Signup and view all the answers

    What is the percentage of sodium chloride present in seawater?

    <p>79%</p> Signup and view all the answers

    Which of the following salts in seawater has the lowest amount in one kilogram?

    <p>Magnesium bromide</p> Signup and view all the answers

    What is the primary purpose of the cooling system on ships?

    <p>To remove unusable heat</p> Signup and view all the answers

    Which ion is most prevalent in seawater based on the provided data?

    <p>Chloride (Cl-)</p> Signup and view all the answers

    What is the amount of calcium carbonate found in one kilogram of seawater?

    <p>0.12 gm</p> Signup and view all the answers

    Which salt has a higher PPM in freshwater samples compared to seawater samples?

    <p>Sodium nitrate</p> Signup and view all the answers

    What is the role of the cooling liquid in the marine engine's cooling system?

    <p>To cool the engine components</p> Signup and view all the answers

    Which of the following contributes the least to the overall PPM of dissolved solids in seawater?

    <p>Calcium bicarbonate</p> Signup and view all the answers

    What is the primary risk associated with using galvanized piping in a diesel cooling system?

    <p>Temperature-induced corrosion of zinc</p> Signup and view all the answers

    Before applying corrosion inhibitors, what is recommended for the zinc galvanizing?

    <p>Removing it through acid treatment</p> Signup and view all the answers

    Which chemical is specified as a corrosion inhibitor protective to cast iron, steel, and aluminum?

    <p>Sodium Nitrite</p> Signup and view all the answers

    What is the recommended dosage range for Sodium Benzoate as a corrosion inhibitor?

    <p>10000 to 15000 ppm</p> Signup and view all the answers

    Which of the following inhibitors is known to provide some alkalinity by buffering at a pH of 8.9?

    <p>Sodium Borate</p> Signup and view all the answers

    What must be tested in the cooling water to determine the proper concentration of inhibitors needed?

    <p>Chloride or sulfate concentration</p> Signup and view all the answers

    Which inhibitor is used for protection against corrosion specifically in copper and copper alloys?

    <p>Sodium Borate</p> Signup and view all the answers

    Which of the following statements is true regarding the use of Zinc in cooling systems?

    <p>Zinc acts as a protective sacrificial metal.</p> Signup and view all the answers

    What should be done if deposits or rust are detected in a cooling water system?

    <p>Conduct a thorough cleaning and refill with newly treated water</p> Signup and view all the answers

    Which procedures are included in the cleaning of a cooling water system?

    <p>Degreasing and descaling procedures</p> Signup and view all the answers

    Who is recommended to carry out the cleaning of the cooling water system?

    <p>A reliable specialist firm</p> Signup and view all the answers

    What should you do if a specialist firm is not available for cleaning the cooling water system?

    <p>Follow instructions from the supplier of cleaning chemicals</p> Signup and view all the answers

    What is a key reason for cleaning the cooling water system?

    <p>To maintain system efficiency and prevent damage</p> Signup and view all the answers

    What characteristic of the cleaning chemicals used in the cooling water system requires caution?

    <p>They may be hazardous</p> Signup and view all the answers

    What happens to the cooling water after cleaning the system?

    <p>It should be completely refilled with newly treated water</p> Signup and view all the answers

    Why is it important to follow specific instructions when cleaning the cooling water system?

    <p>To ensure safe handling of potentially hazardous chemicals</p> Signup and view all the answers

    Study Notes

    Water Chemistry Overview

    • Water is a clear, colorless liquid composed of two hydrogen atoms and one oxygen atom (H2O).
    • Covers over 70% of the Earth's surface and is essential for life.
    • Exists in three phases: solid (ice, ≤ 0°C), liquid (0°C to 100°C), vapor (≥ 100°C).
    • Boiling point: 100°C (212°F); Freezing point: 0°C (32°F).

    Freshwater vs. Saltwater

    • Freshwater: contains < 1% salt, found in lakes, streams, and glaciers; tasteless and odorless.
    • Saltwater: contains ≥ 3% salt, primarily in oceans; unsuitable for human consumption; home to marine organisms like sharks and tuna.

    Composition of Seawater

    • Major components include Sodium Chloride (NaCl), Magnesium Chloride (MgCl2), and Magnesium Sulfate (MgSO4).
    • Sodium Chloride constitutes 79% of dissolved solids in seawater, with approximately 25,000 PPM concentration.
    • Common ions in seawater: Chloride (55.03%), Sodium (30.59%), Sulfate (7.68%).

    Marine Engine Cooling Water System

    • Critical for ships to remove excess heat from engines and machinery.
    • Cooling achieved by circulating liquid around engine passages, preventing overheating and preserving metal properties.

    Quality Requirements for Cooling Water

    • Best suited with demineralized (distilled) water; corrosion inhibitors necessary to prevent environmental corrosion.
    • Rainwater and tap water generally not recommended due to contamination and chalk deposits.
    • Sea water can cause severe corrosion and deposits, hence prohibited as cooling water.

    Corrosion in Cooling Water Systems

    • Corrosion: degradation of materials through chemical or electrochemical reactions.
    • Common forms: general wastage, pitting, crevice, galvanic, stress, and erosion corrosion.
    • Corrosion can form insulating scale, impairing heat transfer.

    Zinc Presence and Corrosion Management

    • Zinc galvanization used for protection against corrosion but may reverse polarity at high temperatures (60°C to 90°C), potentially increasing corrosion.
    • Recommended to remove galvanized elements before adding corrosion inhibitors.

    Chemicals for Cooling Water Treatment

    • Sodium Nitrite (NaNO2): protects cast iron and steel, dosage 1000 to 3000 PPM.
    • Sodium Benzoate (C8H5CO2Na): protective for steel and solder, dosage 10,000 to 15,000 PPM.
    • Sodium Borate (Na2B4O7): offers alkalinity, buffers at pH 8.9, dosage 1000 to 3000 PPM.

    Cleaning Cooling Water Systems

    • Abnormal deposits necessitate thorough cleaning and refilling with freshly treated water.
    • Cleaning involves degreasing and descaling using special chemicals; should be done by specialists following safety protocols.

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    Description

    This quiz covers the key aspects of the physical and chemical properties of cooling water as discussed in Topic 1 Lesson 2. You will explore water chemistry analyses, including the identification and quantification of chemical components. Understand the significance of pure water and its forms in various contexts.

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